SharePoint Web Application could be defined as an IIS Web Site specifically configured to run WSS sites.
So the question arises what is an IIS Web Site?
IIS Web Site could be defined as an entry point in the IIS Web Server infrastructure.
Default web site created listens for incoming HTTP requests on port 80. We could create additional web sites as well, having different port numbers or IP addresses. Every IIS Web site could be configured independently. For e.g. we could have Default Web Site allowing anonymous access and a second IIS Web site that uses integrated authentication.
Creating IIS Web Site
Creating a Web site by using IIS Manager does not create content, but merely creates a directory structure and configuration files from which to publish the content. To publish the Web content, we can place content in the default home directory, or we can create a different home directory or virtual directory and place content there.
Creating or extending WSS Web application
Using Central Administration application we could easily create web site which would be automatically configured to be a WSS Web Application. A new content database gets created for each newly created web application. Normally we would be having one content database per web application. However it is possible to distribute sites within a web application across multiple content databases.
Understanding Content databases
Creating multiple content database in a web application
So what happens when a IIS Web Site is transformed to a WSS Web Application?
- WSS makes few entries into the IIS Metabase.
- Creates virtual directories which maps to 12 hive (installation directory\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\)
- _controltemplates – where user controls are kept.
- _layouts – has application pages in it.
- _vti_bin – dlls and web services repository
- _wpresources – resource file repository for Web Parts
- Adds WSS-specific web.config to the root directory of the IIS Web site.
- Extends routing architecture of IIS and ASP.NET to properly route all incoming requests through WSS runtime.
A single web application could have multiple site collection within it and each site collection has a top level site and could have multiple sub sites in it. A WSS site collection acts as a container of WSS Sites.